Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania) between 637 ka and the present
Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania) between 637 ka and the present
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DOI：
10.5194/bg-13-1179-2016
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发表时间：
2016-01-01
期刊：
影响因子：
4.9
通讯作者：
Giaccio, Biagio
中科院分区：
文献类型：
--
作者：
Francke, Alexander;Wagner, Bernd;Giaccio, Biagio
奥赫里德湖(阿尔巴尼亚马其顿)被认为有120多万年的历史，拥有300多种特有物种。作为国际大陆科学钻探方案的目标，2013年在奥赫里德湖过去物种形成条件科学合作项目的范围内成功地开展了深部钻探活动。在这里，我们提供了来自湖中央569米深的沉积物序列上部247.8米复合深度的岩石学、沉积学和(生物)地球化学数据。根据基于11个Tephra层(一级连接点)的年龄模型和生物地球化学替代数据与轨道参数(二级连接点)的调整，所分析的沉积物序列涵盖了最近637KYR。深部沉积物序列由半远洋沉积组成，其间夹杂着几个盖夫拉层和罕见的薄(<；5厘米)块状消耗性沉积。半深海沉积物可分为三种不同的岩性类型。岩石类型1和2由钙质和轻度钙质粉质粘土组成，主要归因于间冰期，夏季湖泊初级生产力高，冬季混合减少。这些数据表明，在MIS15、13和5期间，湖水中高的离子和营养物质浓度促进了方解石的沉淀和硅藻的生长。在强劲的初级生产力之后，海洋同位素阶段11和5的间冰期温度最高，而MIS15、13、9和7的温度相对较低。岩石类型3由碎屑、粉质粘土物质组成，主要代表冰期，夏季初级生产力较低，冬季混合时间较长，混合强度较大。这些数据表明，奥赫里德湖最严重的冰川状况持续在MIS16、MIS12、MIS10和MIS6期间，而MIS14、MIS8、MIS4和MIS2的温度可能会有所回升。间冰期的条件出现在MIS14和MIS8的部分时间。
Lake Ohrid (Macedonia, Albania) is thought to be more than 1.2 million years old and host more than 300 endemic species. As a target of the International Continental scientific Drilling Program (ICDP), a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project in 2013. Here, we present lithological, sedimentological, and (bio-) geochemical data from the upper 247.8m composite depth of the overall 569m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on 11 tephra layers (first-order tie points) and on tuning of bio-geochemical proxy data to orbital parameters (second-order tie points), the analyzed sediment sequence covers the last 637 kyr. The DEEP site sediment succession consists of hemipelagic sediments, which are interspersed by several tephra layers and infrequent, thin (< 5 cm) mass wasting deposits. The hemipelagic sediments can be classified into three different lithotypes. Lithotype 1 and 2 deposits comprise calcareous and slightly calcareous silty clay and are predominantly attributed to interglacial periods with high primary productivity in the lake during summer and reduced mixing during winter. The data suggest that high ion and nutrient concentrations in the lake water promoted calcite precipitation and diatom growth in the epilimnion during MIS15, 13, and 5. Following a strong primary productivity, highest interglacial temperatures can be reported for marine isotope stages (MIS) 11 and 5, whereas MIS15, 13, 9, and 7 were comparably cooler. Lithotype 3 deposits consist of clastic, silty clayey material and predominantly represent glacial periods with low primary productivity during summer and longer and intensified mixing during winter. The data imply that the most severe glacial conditions at Lake Ohrid persisted during MIS16, 12, 10, and 6, whereas somewhat warmer temperatures can be inferred for MIS14, 8, 4, and 2. Interglacial-like conditions occurred during parts of MIS14 and 8.